The present invention relates to a data sharing system for sharing display screen data between a plurality of terminal apparatuses, as well as to a transmitting terminal apparatus, a transmitting terminal apparatus controlling method, a receiving terminal apparatus, a receiving terminal apparatus controlling method, and a recording medium which stores programs, all for use by the system.
There exist systems today each designed to transfer data between a plurality of terminal apparatuses connected via a network so that the data may be shared between the connected apparatuses. One such system is a display screen sharing system that has display screen data shared by a plurality of terminals connected via a network illustratively for networked conference purposes. In a conference based on the system, a presenter's terminal apparatus (i.e., transmitting terminal apparatus) transmits display screen data that are received by other participants' terminal apparatuses (receiving terminal apparatuses) for display on their screens. The participants in the networked conference are thus able to view what is being presented by the presenter.
Such a data sharing system generally has interlocking functions in effect between a transmitting terminal apparatus and receiving terminal apparatuses. The interlocking functions illustratively include: a remote operation capability allowing any one of the receiving terminal apparatuses displaying the shared screen data to let the user operate on the display screen so as to remotely operate the transmitting terminal apparatus; a file transfer capability enabling the receiving terminal apparatuses to receive and store files sent from the transmitting terminal apparatus; and a chat capability permitting users of a plurality of terminals to chat with messages on their screens in real time.
When the system outlined above transmits display screen data, it is customary for the system to stick to a predetermined transfer rate for data transmission based on previously assumed communication conditions. However, the ongoing network communication status typically varying from moment to moment can differ significantly from the presupposed communication conditions. That can result in a huge loss of time in transmitting data. For example, if the actual network bandwidth at the time of transmission happens to be greater than the presupposed network bandwidth, each packet could potentially transport more data than planned but is bound to convey a predetermined small amount of data. That is inefficient and wasteful.
In another example, if there occur delays or losses in data transfers, the interlocking process between the transmitting and the receiving terminal apparatuses may well end up faulty. Under these conditions, real-time-oriented capabilities such as remote operation and chat can effectively cease functioning. Conventionally, however, these functions are left apparently operable even though they are not. The user may then select or try to operate these functions without realizing they are currently unavailable. This can result in a significant decline in the user's work efficiency.
The present invention has been made in view of the above circumstances and provides a data sharing system for permitting efficient data transfers and concomitant interlocking processes between a plurality of terminal apparatuses depending on the communication status of a network connecting the apparatuses; as well as a transmitting terminal apparatus, a transmitting terminal apparatus controlling method, a receiving terminal apparatus, a receiving terminal apparatus controlling method, and a recording medium which stores programs, all for use by the system.